This invention pertains to a stop-leak composition for cooling systems of internal combustion engines and the like. The composition is placed into the liquid of the cooling system, in which it disperses. In the event of a pinhole leak, the composition in drawn to the leak to plug it in a spontaneous manner.
Precursor compositions are found in the prior art, as described in U.S. Pat. Nos. 4,348,235 and 4,662,940. Specifically, compositions of the prior art comprise a mixture of ginger rhizome powder mixed with ground nut shells, and typically including other additives such as boric acid, magnesium stearate, and sodium lignin sulfonate.
By this invention, significantly improved formulations are provided which exhibit better sealing characteristics at a significantly reduced materials cost. Also, some formulations of this invention are readily formed into non-friable tablets which do not readily crumble or chip on handling, but which easily disperse when placed into the aqueous environment of a liquid cooling system for an internal combustion engine, to provide the desired sealing characteristics. Furthermore, preferred products of this invention do not discolor the specific commercially available radiator coolant liquids, which typically carry a bright, characteristic color. Also, the preferred compositions of this invention do not significantly react with the coolant inhibitor package.
By one aspect of this invention, a stop-leak composition is provided for cooling systems of internal combustion engines and the like. The stop-leak composition consists essentially of a powder comprising from 25 to 100 weight percent of ground wood or substantially pure cellulose powder, any balance of the powder comprising ginger rhizome powder. This is preferably mixed with ground nut shells, typically pecan, almond, or other hardwood nut shells. The ground wood/cellulose, and ginger rhizome powder when present, may preferably be present in the final formulation in an amount of 40 to 95 weight percent, while the ground nut shells are preferably present in an amount of about 5 to 60 weight percent.
Other additives may also be present as desired, for example the additives disclosed in the previously cited patents such as boric acid powder, typically present in an amount of 1.5 to 3.5 weight percent; an alkali metal lignin sulfonate such as sodium lignin sulfonate, typically present in an amount of 3 to 6 weight percent; or an alkaline earth soap such as magnesium stearate, typically present in an amount of 0.5 to 2 weight percent. However, these optional ingredients are not necessary for all applications and, in fact, may be absent from currently-preferred compositions.
It is also currently preferred in some embodiments for the ground wood to be present in the amount of about 100 weight percent of the above-stated powder, with the ginger rhizome being essentially absent. By this invention, it has been found that the ground wood, preferably ground hardwood, operates as well or better as an ingredient along with ground nut shells, when compared with the ginger rhizome powder, but the ground hardwood used has a cost per pound which is on the order of one eighth the cost of the ginger rhizome powder. The mixture of the ground wood and the nutshells provide an effective, water dispersable, leak-sealant composition, optionally without the use of other additives. The ground wood may preferably be present in the amount of 40 to 70 weight percent, the balance being ground nut shells.
The ground nut shells provide a desirable abrasive action on the water pump seals of the cooling system, to remove precipitated deposits of carbonate and the like.
The ground wood provides much of the sealing capability, to close off small leaks from the cooling system.
Some of the additives of the prior art can be dispensed with because the composition of this invention comprising a mixture of ground wood and ground nut shells can, by this invention, be sealed as a loose powder in a water soluble film package such as polyvinyl alcohol and thus does not need to be formed into a unitary mass. This packaging may be accomplished in a conventional manner with known package forming machines, for example, in accordance with the packaging method and apparatus illustrated in Cloud, U.S. Pat. No. 3,218,776. Such packages are easily stored and handled, and may simply be dropped into the liquid cooling system of the internal combustion engine that is to be protected. This may be done during the manufacturing process if desired, or later in the life of the motor. Alternatively, the packaging may be formed from other water soluble plastics.
When the package comes into contact with the aqueous coolant, the polyvinyl alcohol or other soluble outer film quickly dissolves, and the contents of the container are dispersed in a fairly uniform manner throughout the aqueous coolant, especially when the motor is operating. The powder can be dispersed into the radiator water/coolant mixture in about fifteen to thirty seconds.
Typically, about nine or ten grams of the composition of this invention may be optimally added to a conventional radiator system having about 12-16 liters of coolant. Proportionally greater or lesser amounts may preferably be added to larger or smaller radiator systems.
As for particle sizes, the preferred powdered materials used in the compositions of this invention should pass through about a #30 mesh screen, but not be passed by about a #180 mesh screen, so that the finest particles are generally excluded. Such a particle distribution is optimal for avoidance of plugging the radiator or heater core, while being suitable to plug pin hole and other small leaks. The words xe2x80x9c#30 meshxe2x80x9d and xe2x80x9c#180 meshxe2x80x9d refer to strands per inch.
In another embodiment of this invention, a tablet of stop-leak composition may be provided. These tablets resist crumbling on shipment, but readily disperse in the coolant of a radiator, and readily plug small leaks of the various possible kinds when they form.
Other forms for dispensing the compositions of this invention could include a bottle or tube from which the powder is poured into the radiator, or a liquid/powder blend in a container.
The composition of such a tablet preferably consists essentially of a mixture of 5-30 weight percent of powdered purified cellulose; 25 to 60 weight percent of ground nut shells; and 30 to 70 weight percent of ginger rhizome powder, ground wood, or a mixture thereof.
The powdered, purified cellulose may be microcrystalline cellulose, to serve as a binder. For example, such a product is sold by the Pennwest Pharmaceutical Company under the trademark Emcocelxe2x80x94LP200.
The ground nutshells in this and in the previous embodiment may typically comprise pecan nut shells, although other hardwood nut shells such as walnuts may also be ground up and used.
The ground wood in both of these embodiments is preferably a hardwood such as oak or maple, but softer woods such as pine or spruce may be used as well. Maple is preferred since it does not discolor commercial antifreeze.
The ginger rhizome powder is also commercially available, being a manufacturing by-product of ginger as a spice.
The preferred particle size range for the ground nut shells, ginger rhizome, and ground woods is as indicated above.
The above tablet-forming composition may be formed into a tablet weighing typically about 5-15 grams by simple pressure, with the cellulose providing good binding in the well-mixed composition. A typical tablet may be a cylinder of about 25 mm. diameter and 25 mm. length. Typically, pressures in conventional tablet-forming equipment may be applied on the order of 15 to 40 tons per square inch.